Hildegard Peplau developed the interpersonal relations theory, which describes the phases of the nurse-patient relationship. The theory outlines 4 phases: orientation, identification, exploitation, and resolution. It also identifies key nursing roles to support patients through each phase towards achieving health goals. Peplau's theory emphasizes therapeutic communication between nurses and patients to understand their needs and collaboratively set plans. The theory provides a framework for the nursing process and remains applicable for supporting patients.